Non-gellable bitumen/polymer compositions

ABSTRACT

Non-gellable, high temperature storage-stable bitumen/polymer compositions are provided and which are produced by stirring a sulphur-cross-linkable elastomer, an antigelling adjuvant and a sulphur-donating coupling agent into a bitumen or bitumen mixture at 100°-230° C. The antigelling adjuvant has the formula R--X wherein R is a C 2-50  monovalent organic radical and X is a carboxylic acid, sulfonic acid or phosphoric acid group. The bitumen-polymer compositions may be used directly or in diluted form in a bitumen or bitumen mixture to form bitumen/polymer binders for producing road surfaces, coating materials or sealing materials.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to non-gellable bitumen/polymer compositions whichare stable on storage at high temperature, that is to say, according tothe invention, up to temperatures which may reach values of the order of260° C. The invention also relates to a process for the preparation ofsuch compositions and equally concerns the application of thesecompositions to the production of bitumen/polymer binders which may beused to make coatings and especially road coatings.

2. Background Art

The crosslinking, via sulphur, of unsaturated elastomers, especially ofcopolymers of styrene and a conjugated diene such as butadiene orisoprene, in bitumens leads to bitumen/polymer compositions whichpossess enhanced stability and excellent physico-mechanicalcharacteristics and which may be used to make various coatings,especially road surfacings, mixes or alternatively leaktight coatings,having enhanced characteristics compared with the coatings obtained frombitumens alone.

The preparation of bitumen/polymer compositions of the abovementionedtype, for which the elastomer which is crosslinkable with sulphur is acopolymer of styrene and a conjugated diene, is described in particularin the citations FR-A-2,376,188, (U.S. Pat. No. 4,145,322),FR-A-2,528,439, (U.S. Pat. No. 4,554,313), and EP-A-0,360,656 (U.S. Pat.No. 5,508,112).

The bitumen/polymer compositions of the abovementioned type, from whichbitumen/polymer binders are produced for making coatings, especiallyroad coatings, are prepared in practice at polymer contents below athreshold which may range from about 3% to 6% by weight of bitumendepending on the nature and the molecular weight of the polymer, on theone hand, and the quality of the bitumen, on the other hand, gelling ofthe bitumen/polymer composition which is observed fairly frequentlyduring the preparation of the said composition or while it is stored,occurs as soon as the polymer content of this composition exceeds theabovementioned threshold. It is thus difficult, in practice, to producenon-gellable bitumen/polymer compositions with a high polymer content,which would act as bitumen/polymer concentrates, and are more economicalto prepare and to transport than bitumen/polymer compositions with alower polymer content, and which could be diluted at the time of use, byaddition of bitumen, in order to obtain the correspondingbitumen/polymer binders with a lower polymer content which are usuallyused to make coatings.

SUMMARY OF THE INVENTION

The invention makes it possible to overcome the abovementioned drawbacksby proposing bitumen/polymer compositions of the type including abitumen and an elastomer crosslinked with sulphur, which arenon-gellable, stable on storage at high temperature, that is to say,according to the invention, up to temperatures of the order of 260° C.,and are pumpable by means of conventional systems for pumping moltenbitumens and which may readily be diluted, if need be, with bitumen inorder to produce the bitumen/polymer binders usually used to makecoatings and especially road coatings.

The bitumen/polymer compositions according to the invention are of thetype consisting of a homogeneous mass formed of a bituminous matrixconsisting of a bitumen or of a mixture of bitumens and in which isuniformly distributed an elastomer crosslinked with sulphur, in anamount between 3% and 30% and preferably between 5% and 25% of theweight of the bituminous matrix, and they are characterized in that anadjuvant, acting especially as an anti-gelling agent, is also present inthe bituminous matrix in an amount between 0.1% and 5% and preferablybetween 0.2% and 3% of the weight of the said matrix, the said adjuvantconsisting of one or more compounds of formula R--X, in which R is amonovalent C₂ to C₅₀ and more especially C₂ to C₄₀ organic radical and Xdenotes a functional group chosen from ##STR1## wherein Y representing ahydrogen atom or a radical R.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A process for the preparation of the bitumen/polymer compositionsaccording to the invention is of the type in which, working attemperatures between 100° C. and 230° C. and with stirring for a periodof at least 10 minutes, the bitumen or the mixture of bitumens chosen toconstitute the bituminous matrix is placed in contact with, based on theweight of the bituminous matrix, between 3% and 30% and preferablybetween 5% and 25% of an elastomer which is crosslinkable with sulphurand a sulphur-donating coupling agent in an amount able to give anamount of free sulphur representing 0.1% to 20% and preferably 0.5% to10% of the weight of the polymer which is crosslinkable with sulphur inthe reaction medium formed of the coupling agent, elastomer andbituminous matrix ingredients, and it is characterized in that, duringthe said placing in contact, the reaction medium contains an adjuvantwhich acts in particular as an anti-gelling agent, the said adjuvantbeing used in an amount between 0.1% and 5% and preferably between 0.2%and 3% of the weight of the bituminous matrix and consisting of one ormore compounds of formula R--X, in which R is a monovalent C₂ to C₅₀ andmore particularly C₂ to C₄₀ organic radical and X denotes a functionalgroup chosen from ##STR2## wherein Y representing a hydrogen atom or aradical R.

The bitumen or mixture of bitumens, which is placed in contact with theelastomer which is cross-linkable with sulphur, the anti-gellingadjuvant and the sulphur-donating coupling agent and which constitutesthe bituminous matrix of the bitumen/polymer composition, isadvantageously chosen from the various bitumens which possess akinematic viscosity at 100° C. of between 0.5×10⁻⁴ m² /s and 3×10⁻² ml/sand preferably between 1×10⁻⁴ m² /s and 2×10⁻² m² /s. These bitumens maybe bitumens from direct distillation or from distillation under reducedpressure or alternatively blown or semi-blown bitumens, or even certainpetroleum fractions or mixtures of bitumens and distillates undervacuum. Advantageously, besides a kinematic viscosity within theabovementioned range, the bitumen or mixture of bitumens used to producethe compositions according to the invention has a penetrability, definedaccording to standard NF T 66004, of between 5 and 500 and preferably ofbetween 20 and 400.

The elastomer which is crosslinkable with sulphur, which is used toprepare the bitumen/polymer compositions and which is found crosslinkedin the said compositions, may be such as polyisoprene, polynorbornene,polybutadiene, butyl rubber or ethylene/propylene/diene terpolymer(EPDM). The said elastomer is advantageously chosen from random or blockcopolymers of styrene and a conjugated diene such as butadiene,isoprene, chloroprene, carboxylated butadiene and carboxylated isoprene,and more particular consists of one or more copolymers chosen from blockcopolymers, with or without a random joint, of styrene and butadiene, ofstyrene and isoprene, of styrene and chloroprene, of styrene andcarboxylated butadiene, or alternatively of styrene and carboxylatedisoprene. The copolymer of styrene and conjugated diene, and inparticular each of the abovementioned copolymers, advantageouslypossesses a weight content of styrene ranging from 5% to 50%. The meanviscometric molecular weight of the copolymer of styrene and conjugateddiene, and especially that of the copolymers mentioned above, may bebetween, for example, 10,000 and 600,000 and is preferably between30,000 and 400,000. The copolymer of styrene and conjugated diene ispreferably chosen from the di- or triblock copolymers of styrene andbutadiene, of styrene and isoprene, of styrene and carboxylatedbutadiene or alternatively of styrene and carboxylated isoprene whichhave styrene contents and viscometric molecular weights within theranges defined above.

In the adjuvant of formula R--X defined above, the symbol Radvantageously represents a saturated or unsaturated C₂ to C₅₀ and moreespecially C₂ to C₄₀ monovalent hydrocarbon radical, the said radicalbeing in particular of the linear or branched alkyl or alkenyl type, forexample nonyl, dodecyl, tetradecyl, hexadecyl, octadecyl, octadecenyl,nonadecyl, eicosenyl, docosenyl or tetraco-senyl, of the alkylaryl type,for example nonylphenyl, dodecylphenyl, didodecylphenyl,tetradecylphenyl, dodecyltolyl, nonyltolyl, nonylxylyl, dodecylxylyl,dodecylcumenyl or hexadecylphenyl, of the alkadienyl or alkatrienyltype, for example 2,4-decadienyl, 2,4,6- decatrienyl,9,10-octadecadienyl, or 9,12,15-octadecatrienyl, or alternatively of thepolycyclic type with condensed rings, for example the hydrocarbonresidue obtained by removal of the carboxylic group from a compound suchas abietic acid or a resinous acid derived from abietic acid.Non-limiting examples of anti-gelling adjuvants of formula R--X comprisecarboxylic acids containing a saturated or unsaturated fatty chain, suchas pelargonic acid, lauric acid, palmitic acid, stearic acid, myristicacid, behenic acid, oleic acid, erucic acid, linoleic acid and linolenicacid, alkylarenesulphonic acids bearing one or two saturated orunsaturated fatty chains on the ring, such as nonylbenzenesulphonicacid, dodecylbenzenesulphonic acid, didodecylbenzene-sulphonic acid,nonyltoluenesulphonic acid, nonylxylene-sulphonic acid,dodecyltoluenesulphonic acid and hexa-decylbenzenesulphonic acid,polycyclic acids containing condensed rings, such as abietic acid andthe resinous acids derived from abietic acid, the monohydrocarbyl estersand dihydrocarbyl esters of phosphoric acid, also referred to asmonohydrocarbylphosphoric acids and dihydrocarbylphosphoric acids, forwhich the hydrocarbon radical is chosen from alkyl radicals such asbutyl, ethyl, 2-ethylhexyl, octyl, nonyl, decyl, dodecyl, hexadecyl,9-octadecenyl and octadecyl, mixtures of fatty-chain carboxylic acidsand mixtures of resinous acids and fatty-chain carboxylic acids.

The sulphur-donating coupling agent, which is used in the preparation ofthe bitumen/polymer compositions according to the invention, may consistof a product chosen from the group formed by elemental sulphur,hydrocarbyl polysulphides, sulphur-donating vulcanization acceleratorsand mixtures of such products with each other and/or withnon-sulphur-donating vulcanization accelerators. In particular, thesulphur-donating coupling agent is chosen from the products M whichinclude, by weight, from 0% to 100% of a component A consisting of oneor more sulphur-donating vulcanization accelerators and from 100% to 0%of a component B consisting of one or more vulcanization agents chosenfrom elemental sulphur and hydrocarbyl polysulphides, and the productsN, which include a component C consisting of one or morenon-sulphur-donating vulcanization accelerators and a product M in aweight ratio of the component C to the product M ranging from 0.01 to 1and preferably from 0.05 to 0.5.

The elemental sulphur which may be used to constitute, in part or intotal, the coupling agent is advantageously flowers of sulphur andpreferably sulphur crystallized in the orthorhombic form and known underthe name alpha sulphur.

The hydrocarbyl polysulphides which may be used to form a part or all ofthe coupling agent may be chosen from those which are defined in thecitation FR-A-2,528,439 and which correspond to the general formula##STR3## in which R₁ and R₂ each denote a saturated or unsaturated C₁ toC₂₀ monovalent hydrocarbon radical or are joined together to constitutea saturated or unsaturated C₁ to C₂₀ divalent hydrocarbon radical,forming a ring with the other associated groups of atoms in the formula,R₅ is a saturated or unsaturated C₁ to C₂₀ divalent hydrocarbon radical,the--(S)m--groups representing divalent groups each formed of m sulphuratoms, it being possible for m to be different from one of the saidgroups to another and denoting integers ranging from 1 to 6 with atleast one m being equal to or greater than 2, and x represents aninteger taking values from 0 to 10. Preferred poly-sulphides correspondto the formula R₃ --(S)p--R₃, in which R₃ denotes a C₆ to C₁₆ alkylradical, for example hexyl, octyl, dodecyl, tert-dodecyl, hexadecyl,nonyl and decyl, and--(S) p--represents a divalent group formed by achain of p sulphur atoms, p being an integer ranging from 2 to 5.

When the coupling agent includes a sulphur-donating vulcanizationaccelerator, this accelerator may be chosen in particular from thethiuram polysulphides of formula ##STR4## in which the groups R₄, whichmay be identical or different, each represent a C₁ to C₁₂ and preferablya C₁ to C₈ hydrocarbon radical, especially an alkyl, cycloalkyl or arylradical, or alternatively two radicals R₄ attached to the same nitrogenatom are linked together to form a divalent C₂ to C₈ hydrocarbon radicaland u is a number ranging from 2 to 8. Examples of such vulcanizationaccelerators which may especially be mentioned are the compoundsdipentamethylenethiuram disulphide, dipenta-methylenethiuramtetrasulphide, dipentamethylenethiuram hexasulphide, tetrabutylthiuramdisulphide, tetraethyl-thiuram disulphide and tetramethylthiuramdisulphide.

Other examples of sulphur-donating vulcanization accelerators which mayalso be mentioned are alkylphenol disulphides, and disulphides such asmorpholine disulphide and caprolactam N,N'-disulphide.

The non-sulphur-donating vulcanization accelerators which may be used toform the component C of the coupling agents of product N type may besulphur-containing compounds chosen especially frommercaptobenzothiazole and derivatives thereof, in particular metalbenzothiazole thiolates and especially benzothiazolesulphenamides,dithiocarbamates of formula ##STR5## in which the groups R₄ , which maybe identical or different, have the meaning given above, Y represents ametal and v denotes the valence of Y, and thiuram monosulphides offormula ##STR6## in which groups R₄ have the meaning given above.

Examples of vulcanization accelerators of the mercaptobenzothiazole typemay be such as mercaptobenzothiazole, benzothiazole thiolate of a metalsuch as zinc, sodium or copper, benzothiazyl disulphide,2-benzothiazolepentamethylenesulphenamide,2-benzothiazolethiosulphenamide,2-benzothiazoledihydrocarbylsulphenamides for which the hydrocarbonradical is an ethyl, isopropyl, tert-butyl or cyclohexyl radical, andN-oxydiethylene-2-benzothiazolesulphenamide.

Among the vulcanization accelerators of the dithiocarbamate type ofabovementioned formula, there may be mentioned the compounds:dimethyldithiocarbamates of metals such as copper, zinc, lead, bismuthand selenium, diethyldithiocarbamates of metals such as cadmium andzinc, diamyldithiocarbamates of metals such as cadmium, zinc and lead,and lead or zinc pentamethylenedithiocarbamate.

As examples of thiuram monosulphides having the formula given above,there may be mentioned compounds such as dipentamethylenethiurammonosulphide, tetramethylthiuram monosulphide,tetraethylthiurammonosulphide and tetrabutylthiuram monosulphide.

Other non-sulphur-donating vulcanization accelerators, which do notbelong to the families defined above, may also be used. Suchvulcanization accelerators may be such as 1,3-diphenylguanidine,di-ortho-tolylguanidine and zinc oxide.

For more details on the sulphur-donating and non-sulphur-donatingvulcanization accelerators which may be used to form the coupling agent,reference may be made to the citations EP-A-0,360,656 (U.S. Pat. No.5,508,112) and EP-A-0,409,683, (U.S. Pat. No. 5,120,777) the contents ofwhich are incorporated in the present description by way of reference,along with the contents of citation FR-A-2,528,439 (U.S. Pat. No.4,554,313).

As a result of its composition, as mentioned above, the coupling agentmay be of the monocomponent type or of the multicomponent type, it beingpossible for the coupling agent of the multicomponent type to be formedprior to its use or alternatively produced in situ in the medium inwhich it needs to be present. The coupling agent of the preformedmulticomponent type or of the monocomponent type or the components ofthe coupling agents of the multicomponent type formed in situ may beused as they are, for example in the molten state, or alternatively as amixture, for example in solution or in suspension, with a diluent, forexample a hydrocarbon compound.

The process for the preparation of the bitumen/polymer compositionsaccording to the invention is advantageously carried out by firstplacing the elastomer which is crosslinkable with sulphur and theadjuvant of formula R--X in contact with the bitumen or the mixture ofbitumens intended to form the bituminous matrix of the compositions,using proportions of elastomer and of adjuvant having values, relativeto the bituminous matrix, chosen within the ranges defined above forthese proportions, working at temperatures between 100° C. and 230° C.,more particularly between 120° C. and 190° C., and with stirring, for asufficient period, generally of the order of a few tens of minutes to afew hours and, for example, of the order of 1 hour to 8 hours, in orderto form a homogeneous mixture, and then by incorporating into the saidmixture the sulphur-donating coupling agent in an appropriate amountchosen within the ranges defined above for the said amount and whilekeeping the whole mixture stirring at temperatures between 100° C. and230° C., more particularly between 120° C. and 190° C., and which may ormay not be identical to the temperatures of mixing the elastomer and theadjuvant with the bituminous matrix, for a period at least equal to 10minutes and generally ranging from 10 minutes to 5 hours, moreparticularly from 30 minutes to 180 minutes, in order to form a reactionproduct constituting the non-gellable bitumen/polymer composition.

In the mode of use given above, the adjuvant may be incorporated intothe bitumen or bitumen mixtures before or after the elastomer, it beingequally possible to envisage a simultaneous incorporation. Preferably,the adjuvant is incorporated into the bitumen or mixture of bitumensbefore the elastomer.

The bitumen/polymer compositions according to the invention may alsoinclude various additives and especially promoters of adhesion of thefinal bitumen/polymer binder to mineral surfaces. To do this, the saidadditives may be added to the reaction medium formed of the bitumen ormixture of bitumens, the elastomer which is crosslinkable with sulphur,the adjuvant of formula R--X and the coupling agent, at any particularmoment in the formation of the said reaction medium and preferablybefore addition of the coupling agent to a medium consisting of theother ingredients.

The bitumen/polymer compositions according to the invention arenon-gellable and stable on storage up to high temperatures which mayreach values of the order of 260° C. They may be used as they are orelse diluted with variable proportions of a bitumen or of a mixture ofbitumens in order to constitute bitumen/polymer binders having a chosencontent of crosslinked elastomer, which may either be equal to(non-diluted composition) or else less than (diluted composition) thecontent of cross-linked elastomer in the corresponding initialbitumen/polymer compositions. The bitumen/polymer compositions may bediluted with the bitumen or mixture of bitumens either directly afterthe said compositions have been obtained, when an almost immediate useof the resulting bitumen/polymer binders is required, or alternativelyafter a longer or shorter period of storage of the bitumen/polymercompositions, when a delayed use of the resulting bitumen/polymerbinders is envisaged. The bitumen or mixture of bitumens used to dilutea bitumen/polymer composition according to the invention may be chosenfrom the bitumens defined above as being suitable for the preparation ofthe bitumen/polymer compositions.

The dilution of a bitumen/polymer composition according to the inventionwith a bitumen or a mixture of bitumens in order to form abitumen/polymer binder having a chosen content of crosslinked elastomer,which is less than that of the bitumen/polymer composition, is generallyperformed by bringing together, with stirring and at temperaturesbetween 100° C. and 230° C. and more particularly between 120° C. and190° C., suitable proportions of the bitumen/polymer composition and ofbitumen or mixture of bitumens. For example, the amount of dilutionbitumen or mixture of bitumens may be chosen so that the bitumen/polymerbinder resulting from the dilution of the bitumen/polymer compositionincludes, by weight of the bituminous matrix, between 0.5% and 5% ofcrosslinked elastomer.

The bitumen/polymer binders consisting of the bitumen/polymercompositions according to the invention or resulting from the dilutionof the said compositions with a bitumen or mixture of bitumens, to thedesired content of crosslinked elastomer in the said binders, may beapplied, directly or after placing in aqueous emulsion, to theproduction of road coatings of the surface coating type, to theproduction of mixes laid under hot or cold conditions, or alternativelyto the production of leaktight coatings.

The invention is illustrated by the following examples, which are givenwithout any limitation.

In these examples, the amounts and percentages are expressed by weightexcept where otherwise mentioned.

EXAMPLE 1

Preparation of a control bitumen/polymer composition

Working at 175° C. with stirring, 1,000 parts of a direct distillationbitumen having a penetrability equal to 91, a kinematic viscosity at100° C. of 1.7×10⁻⁴ m² /s, a ring and ball softening point (according tostandard NF T 66 008) equal to 46° C. and a Fraass breaking point(according to standard IP 80/53) equal to -18.5° C., were mixed togetherwith 64 parts of a diblock copolymer of styrene and butadiene having amean viscometric molecular weight equal to about 75,000 and including75% butadiene. After mixing for 5 hours with stirring, a homogeneousmass was obtained.

To the abovementioned homogeneous mass, maintained at 175°C., were thenadded 2 parts of crystallized sulphur and the mixture was stirred forabout another 60 minutes.

A very viscous product having the appearance of a gel which isimpossible to handle was collected.

EXAMPLE 2

Preparation of a bitumen/polymer composition according to the invention

Working at 175° C. with stirring, 10.76 parts of pelargonic acid wereincorporated into 1,000 parts of a bitumen identical to the bitumen usedin Example 1, and the mixture obtained was kept at the said temperaturefor 20 minutes.

While still working at a temperature of 175° C., 64.7 parts of a blockcopolymer identical to that used in Example 1 was then incorporated,with stirring, into the mixture of bitumen and pelargonic acid. Aftermixing for hours with stirring, a homogeneous mass was obtained.

To this homogeneous mass, maintained at 175° C., were then added 2.15parts of crystallized sulphur and the mixture was stirred for aboutanother 60 minutes.

A non-gelled bitumen/polymer composition (product II) was obtained,having the penetrability and ring and ball softening point values givenin Table I compared with those for the pure bitumen (product I.a) andwith those for the control bitumen/polymer composition of Example 1(product I.b).

                  TABLE I                                                         ______________________________________                                                Polymer                 Softening                                             content       Penetrability                                                                           point                                         Product (weight %)    (1/10 mm) (°C.)                                  ______________________________________                                        I.a     0              91       46                                            I.b     6             GEL                                                     II      6             106       87.5                                          ______________________________________                                    

As shown by the data in Table I, the use of pelargonic acid(anti-gelling adjuvant according to the invention) allows thepreparation of a non-gelled bitumen/polymer composition with a highpolymer content (6% by weight) having a markedly improved ring and ballsoftening point. The corresponding control composition prepared in theabsence of pelargonic acid or other adjuvant according to the inventionis gelled and impossible to handle.

EXAMPLES 3 TO 8

Preparation of bitumen/polymer compositions according to the inventionby changing the nature of the anti-gelling adjuvant

The process was performed as described in Example 2, except that thenature of the anti-gelling adjuvant is changed from one example to thenext, the other operating conditions being those of Example 2.

Nature of the anti-gelling adjuvant

Example 3: oleic acid

Example 4: palmitic acid

Example 5: abietic acid

Example 6: mixture of linear C₁₆ to C₁₈ fatty acids and natural resinousacids having the following characteristics:

density at 20° C.: 0.990

acid number: 155 mg KOH/g

saponification number: 160 mg KOH/g

linear C₁₆ to C₁₈

fatty acids: 40%

resinous acids: 50%

unsaponifiable material: 10%

Example 7: mixture of linear natural fatty acids and resinous acidshaving the following characteristics:

density at 20° C.: 0.942

acid number: 185 mg KOH/g

saponification number: 194 mg KOH/g

iodine number: 125

linear C₁₆ to C₁₈

fatty acids: 66%

resinous acids: 30%

unsaponifiable material: 4%

Example 8: distillation residue of a mixture of acids having thefollowing characteristics:

density at 20° C.: 1.075

acid number: 40 mg KOH/g

saponification number: 90 mg KOH/g

resinous acids: 20%

linear C₁₆ to C₁₈

fatty acids: 12%

unsaponifiable material: 68%

The bitumen/polymer compositions obtained are denoted "Product Z.a", Zbeing the example number in Roman numerals.

Each of the bitumen/polymer compositions denoted "Product Z.a" wasdiluted with an equivalent weight of starting bitumen, the process beingperformed with stirring at 175° C. for 60 minutes, to give abitumen/polymer binder denoted "Product Z.b".

The penetrability and RBSP (ring and ball softening point) values of the"Products Z.a" (bitumen/polymer compositions) and the penetrability andRBSP values and the rheological characteristics in traction (accordingto standard NF T 46 002) of the "Products Z.b" (bitumen/polymer bindersobtained by dilution of the compositions) are collated in Table II.

                                      TABLE II                                    __________________________________________________________________________                             Traction Test                                                        Penetrab-                                                                              Temper-                                                        Polymer                                                                             ility                                                                              BRSP                                                                              ature                                                                              Speed                                                                              σt                                                                         σb                                                                         εb                           Production                                                                         Adjuvant                                                                           (weight %)                                                                          (1/10 mm)                                                                          (°C.)                                                                      (°C.)                                                                       (mm/min)                                                                           (bar)                                                                            (bar)                                                                            (%)                                  __________________________________________________________________________    III.a                                                                              Oleic                                                                              6     71   79                                                       III.b                                                                              acid 3     82   53  20   500  1.53                                                                             0.50                                                                             >900                                                           5   500  15.3                                                                             5.26                                                                             867                                  IV.a Palmitic                                                                           6     67   79                                                       IV.b acid 3     81   53  20   500  1.61                                                                             0.58                                                                             >900                                                           5   500  15.6                                                                             4.87                                                                             >900                                 V.a  Abietic                                                                            6     58   78                                                       V.b  acid 3     64   54  20   500  1.85                                                                             0.64                                                                             >900                                                           5   500  17.8                                                                             5.45                                                                             810                                  VI.a Fatty                                                                              6     64   79                                                       VI.b acids                                                                              3     72   53  20   500  1.73                                                                             0.59                                                                             >900                                                           5   500  16.5                                                                             4.77                                                                             700                                  VII.a                                                                              Fatty                                                                              6     67   79                                                       VII.b                                                                              acids                                                                              3     72   54  20   500  1.83                                                                             0.60                                                                             >900                                                           5   500  17 5.14                                                                             >900                                 VIII.a                                                                             Fatty                                                                              6     59   84                                                       VIII.b                                                                             acids                                                                              3     75   54  20   500  1.81                                                                             0.66                                                                             >900                                                           5   500  16.2                                                                             5.69                                                                             >900                                 I.b  None 6     GEL                                                           I.a  None 0     91   46  20   500  1.2                                                                              900                                                               5   500  FRAGILE                                    __________________________________________________________________________     σt: threshold strain                                                    σb: breaking strain                                                     εb: breaking elongation                                          

In view of the results featured in Table II, it still appears that theuse of adjuvants according to the invention, of the fatty acid typehere, allows the preparation of non-gelled bitumen/polymer compositionswith a ring and ball softening point which is substantially enhancedcompared with pure bitumen. The bitumen/polymer binders obtained bydilution of these compositions using bitumen have excellent mechanicalproperties and especially an excellent low-temperature breakingelongation.

The control bitumen/polymer composition (product I.b), prepared in theabsence of adjuvant according to the invention, is gelled and impossibleto handle.

EXAMPLE 9

Preparation of a bitumen/polymer composition according to the inventionusing an adjuvant of the sulphonic acid type

Working at 185° C. with stirring, 3.3 parts of adidodecylbenzenesulphonic acid (benzenesulphonic acid bearing 2 dodecylradicals on the aromatic ring) were incorporated into 1,000 parts of abitumen identical to the bitumen used in Example 1, and the entiremixture was kept at the said temperature for 30 minutes.

While still working at the same temperature and with stirring, 99.5parts of a diblock copolymer of styrene and butadiene which is identicalto that used in Example 1 was then incorporated into the mixture ofbitumen and sulphonic acid. After mixing for 5 hours with stirring, ahomogeneous mass was obtained.

To this homogeneous mass, maintained at 185° C., were then added 2.8parts of crystallized sulphur and the mixture was stirred for aboutanother 60 minutes.

A non-gelled bitumen/polymer composition (product IX.a) including about9% by weight of styrene/butadiene copolymer was obtained.

Table III below gives the penetrability and RBSP values of thecomposition thus obtained, measured during storage of the saidcomposition at high temperature (about 163° C.).

                  TABLE III                                                       ______________________________________                                                Period of storage                                                                            Penetrability                                                                           RBSP                                         Product at 163° C. (hours)                                                                    (1/10 mm) (°C.)                                 ______________________________________                                        IX.a     0             58        92.5                                                  48            60        92.5                                                  96            59        95                                                   144            60        99                                                   240            58        101                                          ______________________________________                                    

By carrying out the preparation of a control bitumen/polymer compositionunder the conditions described above, but in the absence of thesulphonic acid adjuvant, the reaction medium gelled in the reactorimmediately after the addition of sulphur.

Using the bitumen/polymer composition obtained above (product IX.a), abitumen/polymer binder (product IX.b) containing 3% styrene/butadienecopolymer was prepared. To do this, 100 parts of the said composition,withdrawn 120 minutes after introduction of the sulphur, were mixed with200 parts of the pure starting bitumen, the mixing operation beingperformed with stirring at 185° C. for 90 minutes.

Table IV gives the penetrability and RBSP values as well as the tractionproperties of the bitumen/polymer binder (product IX.b) obtained.

                  TABLE IV                                                        ______________________________________                                                          Traction at 5° C. and                                                  500 mm/min                                                          Penetrability                                                                             RBSP    σt                                                                             σb                                                                           εb                            Product (1/10 mm)   (°C.)                                                                          (bar)  (bar)                                                                              (%)                                   ______________________________________                                        IX.b    70          57.5    19.93  7.67 >900                                  ______________________________________                                    

EXAMPLE 10

Preparation of a bitumen/polymer composition according to the inventionusing an adjuvant of the sulphonic acid type

The process was performed as described in Example 9, except that theadjuvant was replaced by the same amount of a xylenesulphonic acidbearing a linear C₁₆ to C18 fatty alkyl radical on the ring, the saidacid having a molar mass of 430.

A non-gelled bitumen/polymer composition (product X.a) including about9% styrene/butadiene copolymer was obtained.

Table V gives the penetrability and RBSP values for the composition thusobtained, measured during storage of the said composition at hightemperature (about 163° C.) for several days.

                  TABLE V                                                         ______________________________________                                                Period of storage                                                                            Penetrability                                                                           RBSP                                         Product (hours)        (1/10 mm) (°C.)                                 ______________________________________                                        X.a      0             61        90.6                                                  48            60        91                                                    72            60        94                                                   120            58        96                                                   240            55        98                                           ______________________________________                                    

EXAMPLE 11

Preparation of a bitumen/polymer composition according to the inventionusing an adjuvant of the alkylphosphoric acid type

Working at 185° C. with stirring, 16 parts of an equimolar mixture ofmono- and bis(2-ethylhexyl)phosphoric acids, prepared by reaction of2-ethylhexanol and phosphorus pentoxide in a 3:1 molar ratio, wereincorporated into 1,000 parts of a bitumen identical to the bitumen usedin Example 1, and the mixture was kept at a temperature of 185° C. for20 minutes.

While still working at the same temperature with with stirring, 88 partsof a diblock copolymer of styrene and butadiene which is identical tothat used in Example 1 was then incorporated into the mixture of bitumenand phosphoric adjuvant. After mixing for 5 hours with stirring, ahomogeneous mass was obtained.

To the said homogeneous mass, maintained at 185° C., were then added 2.3parts of crystallized sulphur and the mixture was stirred for aboutanother 60 minutes.

A non-gelled bitumen/polymer composition (product XI.a) including about8% by weight of styrene/butadiene crosslinked copolymer was obtained.

Table VI below gives the penetrability and RBSP values for thecomposition thus obtained, measured during storage of the saidcomposition at high temperature, namely about 160° C.

                  TABLE VI                                                        ______________________________________                                                Period of storage                                                                            Penetrability                                                                           RBSP                                         Product at 163° C. (hours)                                                                    (1/10 mm) (°C.)                                 ______________________________________                                        XI.a     0             50        86                                                    48            51        88                                                    96            49        89                                                   144            49        89                                                   240            47        91                                           ______________________________________                                    

By carrying out the preparation of a control bitumen/polymer compositionunder the operating conditions of the present example, but in theabsence of the phosphoric adjuvant, the reaction medium gelledimmediately after addition of the sulphur.

EXAMPLE 12

Preparation of a bitumen/polymer composition according to the inventionusing an adiuvant of the alkylphosphoric acid type

The process was performed as described in Example 9, except that theadjuvant of Example 9 was replaced by the same amount of an equimolarmixture of mono- and diethylphosphoric acids.

A non-gelled bitumen/polymer composition having a dynamic viscosity at140° C. equal to 21 Poises and including about 9% of crosslinkedstyrene/butadiene diblock copolymer (product XII.a) was thus obtained.

Table VII below gives the penetrability and RBSP values for the saidcomposition thus obtained, measured during storage of this compositionat high temperature, namely about 163° C.

                  TABLE VII                                                       ______________________________________                                                Period of storage                                                                            Penetrability                                                                           RBSP                                         Product at 163° C. (hours)                                                                    (1/10 mm) (°C.)                                 ______________________________________                                        XII.a    0             54        87                                                    48            52        87                                                    96            52        88                                                   240            51        88                                           ______________________________________                                    

We claim:
 1. Non-gellable bitumen/polymer compositions which are stableon storage at high temperature, in the form of a homogenous mass formedof a bituminous matrix comprised of a bitumen or of a mixture ofbitumens and in which there is uniformly distributed an elastomercrosslinked in situ with sulphur, in an amount between 3 and 30% of theweight of the bituminous matrix, and wherein an adjuvant, acting as ananti-gelling agent, is also present in the bituminous matrix in anamount between 0.1% and 5% of the weight of the said matrix, saidadjuvant consisting of one or more compounds of formula R--X, in which Ris a monovalent organic radical with 2 to 50 carbon atoms and X isselected from the group consisting of ##STR7## and Y represents ahydrogen atom or said radical R.
 2. Compositions according to claim 1,wherein the adjuvant is present in the bituminous matrix in an amountbetween 0.2 % and 3 % of the weight of the said matrix.
 3. Compositionsaccording to claim 1 wherein the formula R--X representing the adjuvant,the radical R is a monovalent organic radical with 2 to 40 carbon atoms.4. Compositions according to claim 1 wherein, in the formula R--Xrepresenting the adjuvant, the radical R is saturated or unsaturatedmonovalent hydrocarbon radical.
 5. Compositions according to claim 4,wherein the said radical R is a linear or branched alkyl or alkenyl,alkylaryl, alkadienyl, alkatrienyl or polycyclic containing condensedrings.
 6. Compositions according to claim 1 wherein the compounds offormula R--X are selected from the group consisting of carboxylic acidscontaining a saturated or unsaturated fatty hydrocarbon chain,alkylarenesulphonic acids bearing one or two saturated or unsaturatedfatty hydrocarbon chains on the arene ring, polycyclic acids containingcondensed rings, abietic acid and resinous acids derived from abieticacid, monoalkylphosphoric acids, dialkylphosphoric acids and mixtures offatty-chain carboxylic acids and resinous acids.
 7. Compositionsaccording to claim 1 wherein the elastomer crosslinked with sulphuramounts between 5 % and 25 % of the weight of the bituminous matrix. 8.Compositions according to claim 1 wherein the bitumen or the mixture ofbitumens constituting the bituminous matrix are chosen from bitumenshaving a kinematic viscosity at 100° C. of between 0.5×10⁻⁴ m² /s and3×10⁻² m² /s.
 9. Compositions according to claim 8 wherein the saidbitumen have a kinematic viscosity of between 1×10⁻⁴ m² /s and 2×10⁻² m²/s.
 10. Compositions according to claim 1 wherein the bitumen or mixtureof bitumens constituting the bituminous matrix has a penetrability,defined according to standard NF T 66004, of between 5 and
 500. 11.Compositions according to claim 10, wherein the said penetrability is ofbetween 20 and
 400. 12. Compositions according to claim 1 wherein thecrosslinked elastomer distributed in the bituminous matrix is acrosslinked random or block copolymer of styrene and a conjugated diene.13. Compositions according to claim 12, characterized in that the saiddiene is selected from the group consisting of butadiene, isoprene,chloroprene, carboxylated butadiene and carboxylated isoprene. 14.Compositions according to claim 12 wherein the crosslinked random orblock copolymer of styrene and conjugated diene has a weight content ofstyrene ranging from 5% to 50%.
 15. A process for the preparation ofnon-gellable bitumen/polymer compositions which are stable on storage ata high temperature, said process being one in which, working attemperatures between 100° C. and 230° C. and with stirring for a periodof at least 10 minutes, a bitumen or a mixture of bitumens is placed incontact with, based on the weight of the bitumen, between 3% and 30% ofan elastomer which is crosslinkable with sulphur and a sulphur-donatingcoupling agent in an amount able to give an amount of free sulphurrepresenting 0.1% to 20% of the weight of the polymer which iscrosslinkable with sulphur in the reaction medium formed of the couplingagent, elastomer and bitumen ingredients, and wherein during the saidplacing in contact, the reaction medium contains an adjuvant which actsas an anti-gelling agent, said adjuvant being used in an amount between0.1% and 5% of the weight of the bitumen and consisting of one or morecompounds of the formula R--X, in which R is a monovalent organicradical with 2 to 50 carbon atoms and X is selected from the groupconsisting of ##STR8## and Y represents a hydrogen atom or said radicalR.
 16. Process according to claim 15, wherein the adjuvant is present inthe reaction medium in an amount between 0.2% and 3% of the weight ofthe bitumen.
 17. Process according to claim 15 wherein in the formulaR--X representing the adjuvant, the radical R is a monovalent organicradical with 2 to 40 carbon atoms.
 18. Process according to claim 15wherein in the formula R--X representing the adjuvant, the radical R isa saturated or unsaturated monovalent hydrocarbon radical.
 19. Processaccording to claim 18, wherein the said radical R is linear or branchedalkyl or alkenyl, alkylaryl, alkadienyl, alkatrienyl or polycycliccontaining condensed rings.
 20. A process according to claim 15 whereinthe compounds of formula R--X are selected from the group consisting ofcarboxylic acids containing a saturated or unsaturated fatty hydrocarbonchain, alkylarenesulphonic acids bearing one or two saturated orunsaturated fatty hydrocarbon chains on the ring, polycyclic acidscontaining condensed rings, abietic acid and resinous acids derived fromabietic acid, monoalkylphosphoric acids, dialkylphosphoric acids andmixtures of fatty-chain carboxylic acids and resinous acids.
 21. Processaccording to claim 15 wherein the elastomer which is crosslinkable withsulphur is used in an amount representing between 5% and 25% of theweight of the bitumen.
 22. Process according to claim 15 wherein thebitumen or mixture of bitumens has a kinematic viscosity at 100° C. ofbetween 0.5×10⁻⁴ m² /s and 3×10⁻² m² /s.
 23. Process according to claim22, wherein the said viscosity is between 1×10⁻ m² /s and 2×10⁻² m² /s.24. Process according to claim 15 wherein the bitumen or mixture ofbitumens has a penetrability, defined according to standard NF T 66004,of between 5 and
 500. 25. Process according to claim 24, wherein thesaid penetrability is between 20 and
 400. 26. Process according to claim15 wherein the elastomer which is crosslinkable with sulphur is of thetype random or block copolymer of styrene and a conjugated diene. 27.Process according to claim 26, wherein the said diene is selected fromthe group consisting of butadiene, isoprene, chloroprene, carboxylatedbutadiene and carboxylated isoprene.
 28. Process according to claim 26wherein the copolymer of styrene and conjugated diene includes 5 to 50 %by weight of styrene.
 29. Process according to claim 26 wherein the meanviscometric molecular weight of the copolymer of styrene and conjugateddiene is between 10,000 and 600,000.
 30. Process according to claim 29,wherein the said molecular weight is between 30,000 and 400,000. 31.Process according to one of claim 15 wherein the sulphur-donatingcoupling agent is chosen from the group consisting of elemental sulphur,hydrocarbyl polysulphides, sulphur-donating vulcanization accelerators,and mixtures of such products with each other and withnon-sulphur-donating vulcanization accelerators.
 32. Process accordingto claim 15 wherein the sulphur-donating coupling agent is used in anamount able to give an amount of free sulphur representing 0.5% to 10%of the weight of the polymer which is crosslinkable with sulphur. 33.Process according to claim 15 wherein the elastomer which iscross-linkable with sulphur and the adjuvant are first placed in contactwith the bitumen or mixture of bitumens, working at temperatures between100° C. and 230° C. and with stirring for a period of 1 hour to 8 hours,in order to form a homogeneous mixture, and then by incorporating intothe said mixture the sulphur-donating coupling agent the whole mixtureis kept stirring at temperatures between 100° C. and 230° C. and whichmay or may not be identical to the temperatures of mixing the elastomerand the adjuvant with the bitumen, for a period ranging from 10 minutesto 5 hours in order to form the bitumen/polymer composition.
 34. Processaccording to claim 33, wherein the adjuvant is incorporated into thebitumen or mixture of bitumens before the elastomer.